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Steve, BMW Expert
Category: BMW
Satisfied Customers: 23889
Experience:  BMW Expert
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How do you troubleshoot a radiator fan not working? I have

Customer Question

How do you troubleshoot a radiator fan not working?
Hello, I have an overheating 2003 BMW 325ci, the fan never engages, I dont know if it might be the coolant temperature sensor, wiring, or the fan itself. how can I troubleshoot it? thank you.
Submitted: 1 year ago.
Category: BMW
Expert:  Steve replied 1 year ago.

do you have a factory BMW scan tool?

Customer: replied 1 year ago.

I dont have a BMW scan tool, I only have an Autel AL619 scanner

Expert:  Steve replied 1 year ago.

I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.

this fan can only be tested with a factory BMW scan tool which can command it to run in a test mode

most of the time when the fan stops running, the fan itself is the problem.

the fan will run in response to engine temp or to AC system pressure, so if it never comes on, the issue cannot simply be a sensor and wiring issues are exceedingly rare

if you don't have a BMW factory scan tool then I would check the fuse for the fan and if it is good, replace the fan

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 1 year ago.
Can I jump the an directly to see if works? Also, what wires can I check to see if the fan is receiving power.?
Expert:  Steve replied 1 year ago.

Please do not forget to CLICK ON a positive rating

no you cannot jump the wires because the fan always has constant power and ground and is triggered via computer signal from the ECU

power comes in on the red/blue wire

as the question has been answered please kindly CLICK ON a positive rating